Process for producing soap



Patented July '2,

UNITED STATES PATENT OFFICE.

ADOLF WELTER, OF DKEIRINGWERKE, GERMANY.

ITROC ESS FOR PRODUCING SOAP.

This invention relates to processes for producing soap and moreparticularly durable soaps made by the milling process that do notchange through influences of the air or 2 weather.

Efl'ortshave long been made to produce soaps that will keepindefinitely, that do not become unsightly when stored for long periods,whose weight does not change appreciably and which retain their originalshape even in the tropics. The only soaps that will meet theserequirements are the soaps made by the milling process; they are formedor cut into strips by being passed through pairs of rolls and thenpressed into cakes. These soaps will keep for practically any length oftime because they have a high content of fatty acid and a low contentofwater. Theonly known method of producing them, apart from thecompressing of pure, non-hydrous,

powdered soap, has consisted hitherto in milling. In the milling processliquid high grade grain soap is first solidified, and then cu't'intoslices or rolled into bands so as to make it present as large a surfaceas possible in the ensuing drying process. Although this drying processhas recently been greatly improved by the use of ingeniously designeddevices it still requires an amount of heat,

time and labor that is high in proportion to the value of the soapobtained. After the content of water has been reduced by this. knownmethod to such an extent that the content offatty acid is about 80% thehard soap is capable of being milled. The highest content of water atwhich the milling is pos sible at all is about 14 to 15% (see Schrauth,

- Medikamentose Seifen 1914, page 30).

Inpractice it is, however, not advisable 1:0

s to the content of fatty acid this must not be lower than 75% and themost favorable content for milling is 7980%. Now I have found that, ifthe water in a hydrous soap is partly or completely substituted bybicarbonate of sodium, it is possible to make easily millable anddurable soaps even if the content of fatty acid is as low as 60 to 75%.The only process known up to the present by which such soaps containingbicarbonate of sodium can be made cheaply consists in allowing fattyacids that are free of neutral Drawing. Application fileii June 2a,1926, Serial is. 119,225, and in Germany m s, 1925.

most one molecule of soda is used the followmg equation will hold:

' RCOOH+Na,GO

RCOONa+NaHCO Now it has been found that, if fatty acids free of neutralfat as described are made to react on a maximum of one molecule of sodaatabout the melting temperature of the fatty acids and liquid or solidgrain soap or even soappaste is added before, or even after, thesapomfication is quite complete, a soap mixture is obtained which can beeasily and perfectly milled and which has all the desirable propertiessuch as durability, uniformity of composition, immutability of weightand shape. Quite contrary to expectation this millability of the soapmixture was found to exist even when its content of fatty acid droppedto 60%,"and even then rigorous conditions could be maintained in themethod of operation and imposed on the quality of the final product. Itis, therefore, possible to produce high grade or grain soaps in thismanner whose composition corresponds to that of ordinary grain soapbutwhich greatly surpass it in respect to external appearance anddurability. My novel process has, however, further advantages which willnow be gone into.

It is well known that in milling grain soap the palm kernel or cocoanutoil content can only be up to 15% if 20% is exceeded trouble ensues whenmilling. My' aforedescribed process, however, makes it possible notonly'to greatly increase the content of cocoanut or palm kernel oil, butit even renders it possible to use this oil alone, which is extremelyimportant as far as the solubility, foam forming qualities and theutility of the soap in seawater is concerned.

It is to be particularly noted that the aforedescribed processsupercedes by far all hitherto known processes in regard to economy andsimplicity and that it enables a large production to be achieved evenwith a small plant. Just as important is the fact that it enablesmarketable, nice-looking soap to be made from the prepared fatty acidsin one to two hours,- whereas the time re uired with known processeseven with a per ect plant was several days. My novel process alsoenables a part of the soda to be replaced by crystallized sodiumcarbonate (washing soda) or by potash and permits of the use of resin.Furthermore fat solvents such as hydrocarbon bodies, for examplenaphtha, kerosene, or benzol, hydro-naphthaline, hydro-phenol,carbon-tetraohloride or the like may be used in the first stage ofsaponification or mixed with grain soap or soap paste to obtain milledsoaps with a content of fat solvents.

Example 1. 1000 kgs. of palm kernel oil fatty acid or cocoanut oil fattyacid, containing more than 99% of free fatty acid, are mixed with 360kgs. of water-free sodium carbonate. This gives a uniform substancewhich saponifies after a while by spontaneous heatin Before the processof saponification is en ed and before the substance has completelysolidified, 700 to 800 kgs. of liquid grain soap, made from tallow orbone fat, is added. By stirring or mixing these ingredients an almosthomogeneous soap is obtained in a short time which after one hour can bemilled in a milling machine into ribbons. These ribbons can be formedimmediately, or after they have been stored for a short period, intobars by a plodder or compressor and then cut into cakes or tablets.

Example 2.

substance is a thin liquid and perfectl .homogeneous. After a shortwhile it becomes warm and hardens, its temperature rising to 60 to 65 C.The saponification is complete in a few hours and the substance is thensoluble in distilled water at a temperaure of fectly uniform and whoseexterior does not differ in the least from the usual fine soap ribbons.These ribbons can be easily plodded, cut, and pressed, and theirdurability is in no wise inferiorto that of the finest soaps.

I claim A a process for producing air-resisting moulded soap consistingin mixing commercial fatty acids at about their melting point with aquantity of alkali carbonate free from water, sufiicient to saponify upto twice the quantity of fatty acids present, and after saponification,admixing grain soap there with and thereupon subjecting the product thusobtained to the milling process.

In testimony whereof I have afiixed my signature.

ADOLF WELTER.

